(Purin-6-yl) amino acid and production method thereof

ABSTRACT

The invention provides a synthetic method of (purin-6-yl)amino acids which are useful as medicaments of anticancer, anti-virus agents and so on or their intermediates. Methyl (R,S)-3-[4-(9-benzylpurin-6-yl) phenyl]-2-[(t-butoxycarbonyl) amino]propanoate is produced by making 9-benzyl-6-iodopurine react with methyl (R,S)-2-[(t-butoxycarbonyl)amino]-3-[4-(trimethyl-stananyl) phenyl]propionate in the presence of Pd 2  dba 3 , triphenylarsine and copper iodide.

TECHNICAL FIELD

The present invention relates to new (purin-6-yl)amino acid and aproduction method thereof.

BACKGROUND ART

As an anticancer agent or a compound having an antiviral activity,purine compound is conventionally well known, and there are many reportson synthetic intermediates therefor (e.g., WO00/751588).

An object of the present invention is to provide a new(purin-6-yl)amino-acid which itself is useful as a pharmaceuticalproduct such as an anticancer agent, an antiviral agent and the like, aproduction intermediate is therefor and a production method thereof.

SUMMARY OF THE INVENTION

The present invention provides a (purin-6-yl)amino acid represented bythe following formula (1)

wherein

-   R¹ is a hydrogen atom, an alkyl group, an optionally substituted    aryl group, an optionally substituted heteroaryl group or an aralkyl    group;-   R² and R³ are each a hydrogen atom, a halogen atom, an optionally    substituted alkyl group, an optionally substituted aryl group, an    optionally substituted heteroaryl group, an optionally substituted    amino group or an optionally substituted hydroxyl group;-   R is —NH₂, —NHR′ or —NR′R″;-   R′ and R″ are each an amino-protecting group;-   Y is alkylene, alkenylene or alkynylene;-   A is an optionally substituted phenylene;.-   m and n are each 0 or 1; and-   R⁴ is a hydrogen atom or an organic group;    and a salt thereof.

DETAILED DESCRIPTION OF THE INVENTION

In the (purin-6-yl)amino acid represented by the above formula (1) ofthe present invention, as the alkyl group for R¹, C1-C15 alkyl groupsuch as methyl group, ethyl group, n-propyl group, iso-propyl group,n-butyl group, iso-butyl group, sec-butyl group, t-butyl group, n-pentylgroup, iso-pentyl group, neo-pentyl group, n-hexyl group, heptyl group,octyl group, nonyl group, dodecyl group and the like can be mentioned;as the optionally substituted aryl group, for example, aryl group (e.g.,phenyl group, naphthyl group etc.) optionally substituted by theabove-mentioned alkyl group, halogen atom (e.g., chlorine atom, bromineatom), nitro group, hydroxyl group, cyano group, carboxyl group and thelike can be mentioned, which is specifically exemplified by phenylgroup, naphthyl group, tolyl group, xylyl group, 4-oxyphenyl group,4-chlorophenyl group, 4-nitrophenyl group and the like; and as theoptionally substituted heteroaryl group, for example, heteroaryl group(e.g., 2-pyridyl group, 2-quinolyl group, 2-pyrimidyl group,2-thiophenyl group etc.) optionally substituted by alkyl group, cyanogroup, carboxyl group, nitro group, halogen atom and the like can bementioned, and as the aralkyl group, benzyl group and the like can bementioned.

As the halogen atom for R¹ or R³, fluorine atom, chlorine atom, bromineatom, iodine atom and the like can be mentioned; as the optionallysubstituted alkyl group, for example, linear, branched or cyclic C1-C15alkyl group optionally substituted by C7-C15 aralkyloxy group (benzyloxygroup, 1-phenethyloxy group, 2-phenethyloxy group etc.), C1-C7 acylgroup (acetyloxy group, trimethylacetyloxy group, benzoyloxy groupetc.), tri(C1-C7 alkyl)silyloxy group (trimethylsilyloxy group,triethylsilyloxy group, tert-butyldimethylsilyloxy group etc.), (C1-C7alkyl)oxycarbonyloxy group (tert-butyloxycarbonyl group etc.), C1-C15alkyloxy group (methoxy group, ethoxy group, n-propoxy group, isopropoxygroup etc.) and the like can be mentioned. Specific examples thereofinclude methyl group, ethyl group, n-propyl group, n-butyl group,iso-butyl group, sec-butyl group, t-butyl group, n-pentyl group,iso-pentyl group, neo-pentyl group, n-hexyl group, n-heptyl group,n-octyl group, n-nonyl group, n-dodecyl group, cyclopropyl group,cyclohexyl group, acetyloxymethyl group, benzyloxymethyl group,methoxymethyl group and the like.

As the optionally substituted aryl group, for example, aryl group (e.g.,phenyl group, naphthyl group etc.) which may be substituted by theabove-mentioned C1-C15 alkyl group, the above-mentioned halogen atom,nitro group, hydroxyl group, cyano group, carboxyl group and the like,can be mentioned. Specific examples thereof include phenyl group,naphthyl group, tolyl group, xylyl group, 4-oxyphenyl group,4-chlorophenyl group, 4-nitrophenyl group and the like.

As the optionally substituted heteroaryl group, for example, heteroarylgroup such as furyl group, pyrrolyl group, pyridyl group, quinolyl groupand the like, which may be substituted by the above-mentioned C1-C15alkyl group, the above-mentioned halogen atom, nitro group, hydroxylgroup, cyano group, carboxyl group and the like, can be mentioned.Specific examples thereof include 4-chloro-2-pyridyl group,5-bromo-8-quinolyl group and the like.

As the optionally substituted amino group, for example, amino groupoptionally substituted by C7-C15 aralkyl group (benzyl group,1-phenethyl group, 2-phenethyl group etc.), C1-C7 acyl group (formylgroup, acetyl group, trimethylacetyl group, benzoyl group etc.),tri(C1-C7 alkyl)silyl group (trimethylsilyl group, triethylsilyl group,tert-butyldimethylsilyl group etc.), (C1-C7 alkyl)oxycarbonyl group(tert-butyloxycarbonyl group etc.), C1-C15 alkyl group (methyl group,ethyl group, n-propyl group, isopropyl group etc.) and the like can bementioned. Specific examples thereof include amino group, benzylaminogroup, acetylamino group, diacetylamino group,tert-butyloxycarbonylamino group and alkylamino group (methylaminogroup, ethylamino group, dimethylamino group etc.).

As the optionally substituted hydroxyl group, for example, hydroxylgroup optionally substituted by C7-C15 aralkyl group (benzyl group,1-phenethyl group, 2-phenethyl group etc.), C1-C7 acyl group (acetylgroup, trimethylacetyl group, benzoyl group etc.), tri(C1-C7 alkyl)silylgroup (trimethylsilyl group, triethylsilyl group,tert-butyldimethylsilyl group etc.), (C1-C7 alkyl)oxycarbonyl group(tert-butyloxycarbonyl group) or C1-C15 alkyl group (methyl group, ethylgroup, n-propyl group, isopropyl group etc.) and the like can bementioned. Specific examples thereof include hydroxyl group, benzyloxygroup, acetyloxy group and alkoxy group (methoxy group, ethoxy groupetc.).

The substituent R is represented by —NH₂, —NHR′ or —NR′R″, wherein R′and R″ are amino-protecting groups, and the amino-protecting group isexemplified by C7-C15 aralkyl group (benzyl group, 1-phenethyl group,2-phenethyl group etc.), C1-C7 acyl group (acetyl group, trimethylacetylgroup, benzoyl group etc.), tri(C1-C7 alkyl)silyl group (trimethylsilylgroup, triethylsilyl group, tert-butyldimethylsilyl group etc.), (C1-C7alkyl)oxycarbonyl group (methoxycarbonyl group, ethoxycarbonyl group,t-butoxycarbonyl group etc.), aryloxycarbonyl group (phenoxycarbonylgroup etc.) and C1-C15 alkyl group (methyl group, ethyl group, n-propylgroup, isopropyl group, nonyl group etc.).

These R′ and R″ may form, for example, benzophenoneimine together with Natom.

In addition, the binding group Y is alkylene, alkenylene or alkynylene,each of which having 1 to 5, preferably 1 to 3, carbon atoms. Here,alkylene, alkenylene and alkynylene are used in a wide sense. Forexample, alkylene includes methylene, ethylene and the like, and inaddition, when the number of carbon is 3 or more, polymethylene such astrimethylene represented by —CH₂CH₂CH₂—, wherein the carbons on bothends of linear hydrocarbon have a free valence.

The binding group A is, for example, phenylene optionally substituted bythe above-mentioned C1-C15 alkyl group, the above-mentioned halogenatom, nitro group, hydroxyl group, cyano group, carboxyl group and thelike. Specific examples thereof include 2-methyl-1,4-phenylene,2,6-dimethyl-1,4-phenylene, 5-hydroxy-1,3-phenylene and the like.

In the formula (1), the binding sites of A and Y are specified. In somecases, these binding sites may be inverted, and (Y)_(m) may be bonded onthe purine ring side and (A)_(n) may be bonded on the amino acid side.

In the relationship between n and m of (A)_(n) and (Y)_(m), n and m maybe either 0 or 1, wherein the both are mostly 0, or one of them is 0 andthe other is 1.

R⁴ shows a hydrogen atom or an organic group. As the organic group,tetrahydropyran-2-yl, 2,3,5-tri-O-acetyl-β-D-ribofuranosyl and the like,as well as the above-mentioned various substituents, amino-protectinggroup, sugar group and the like can be mentioned.

Here, the sugar group means a structure wherein the carbon atom of the1-position of the sugar is bonded to nitrogen atom of a purine skeleton.As such sugar, for example, pentose (ribose, arabinose, xylose, lyxoseetc.) and hexose (glucose, mannose, galactose, fructose etc.) as well astheir deoxy-derivatives (2-deoxyribose, 3-deoxyribose, 5-deoxyriboseetc.) can be mentioned. The hydroxyl group of these sugars may beprotected by a protecting group. As the protecting group of hydroxylgroup of sugar chain, for example, methyl group, acetyl group, benzoylgroup, benzyl group, toluyl group, trimethylsilyl group,t-butyldimethylsilyl group and the like can be mentioned.

Preferable embodiments of (purin-6-yl)amino acid of the presentinvention represented by the formula (1) can be largely divided intothree groups.

The first is (purin-6-yl)amino acid represented by the formula (2)

wherein R¹, R², R³ and R⁴ are as defined above, and R⁶ and R⁷ are each aphenyl group. Representative compounds are9-benzyl-6-{(ethoxycarbonyl)[(diphenylmethylidene)amino]methyl}purine,9-(tetrahydrofuran-2-yl)-6-{(ethoxycarbonyl)[(diphenylmethylidene)amino]methyl}purine,9-(2,3,5-tri-β-acetyl-A-D-ribofuranosyl)-6-{(ethoxycarbonyl)[(diphenylmethylidene)amino]methyl}purineand the like.

The second is (purin-6-yl)amino acid represented by the formula (3)

wherein R¹, R², R¹, R⁴, Y and m are as defined above, and R⁸ and R⁹ eachmay be a hydrogen atom or an amino-protecting group.

Here, the amino-protecting group of R⁸ and R⁹ is the same as theaforementioned amino-protecting group.

Of the (purin-6-yl)amino acids represented by this formula (3),(purin-6-yl)amino acid wherein (Y)_(m) is alkylene, particularlymethylene, (purin-6-yl)amino acid, wherein (Y)_(m) is trimethylene,which is represented by the following formula (4)

wherein R¹, R², R³, R⁴, R⁸ and R⁹ are as defined above, and(purin-6-yl)amino acid wherein (Y)_(m) is ethynylene represented by—C≡C— are representative amino acids.

Here, specific examples of the aforementioned (purin-6-yl)amino acidwherein (Y)_(m) is methylene include benzyl(R,S)-3-(9-benzylpurin-6-yl)-2-[(t-butoxycarbonyl)amino]propanoate, andexamples of the (purin-6-yl)amino acid wherein (Y)_(m) is trimethyleneinclude ethyl (R,S)-2-amino-5-(9-benzylpurin-6-yl)pentanoate.

The third is (purin-6-yl)amino acid represented by the formula (5)

wherein R¹, R², R³, R⁴, R⁸, R⁹, Y and m are as defined above.

Here, a compound wherein (Y)_(m) is alkylene, particularly methylene, isrepresentative, and as such compound, methyl(R,S)-3-[4-(9-benzylpurin-6-yl)phenyl]-2-[(t-butoxycarbonyl)amino]propanoatecan be mentioned.

As the salt of the compound represented by the formula (1) of thepresent invention, for example, salts with inorganic acids, salts withorganic acids, salts with inorganic bases, salts with organic bases,salts with amino acids and the like can be mentioned. Examples ofpreferable salts with inorganic acids include hydrochloride,hydrobromide, sulfate and the like. Examples of preferable salts withorganic acids include acetate, trifluoroacetate, tartrate,methanesulfonate and the like. Examples of preferable salts withinorganic bases include alkali metal salts (e.g., sodium salt etc.),alkaline earth metal salts (e.g., calcium salt etc.) and the like.Examples of preferable salts with organic bases include trimethyl aminesalt, triethyl amine salt, pyridine salt and the like. Examples ofpreferable salts with amino acids include lysine salt, aspartate and thelike.

The production methods of (purin-6-yl)amino acid of the presentinvention are described in the following for every group describedabove.

The above-mentioned (purin-6-yl)amino acid represented by the formula(2) can be produced by reacting a halogenated purine compoundrepresented by the formula (6)

wherein X is a halogen atom, and R², R³ and R⁴ are as defined above,with an amino acid derivative represented by the formula (7)

wherein R¹, R⁶ and R⁷ are as defined above.

In both starting compounds represented by the formulas (6) and (7), eachsubstituent of R², R³, R⁴, R¹, R⁶ and R⁷ is required to have asubstituent corresponding to the substituent that the object compoundrepresented by the formula (2) has. For both compounds, the substituentX is particularly preferably iodine atom, from among halogen atoms suchas chlorine atom, bromine atom, iodine atom and the like, from theaspect of reactivity.

Of such starting compounds, as the halogenated purine compoundrepresented by the formula (6), for example, 9-benzyl-6-iodoprine,9-(tetrahydrofuran-2-yl)-6-iodoprine,9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-6-iodoprine, and chlorides andbromides instead of iodides of these can be mentioned. From the aspectof reactivity, iodide is preferable.

As the amino acid derivative represented by the formula (7), moreover,glycine derivative, such as ethyl [(diphenylmethylidene)amino]acetate,t-butyl [(diphenylmethylidene)amino]acetate and the like can bementioned.

This method is performed in the presence of a base and a palladiumcatalyst and conventionally in a solvent. As the base, carbonate,phosphate, hydride and the like of alkali metal and alkaline earth metalcan be mentioned. Specific examples thereof include potassium carbonate,sodium carbonate, magnesium carbonate, potassium phosphate, sodiumphosphate, sodium hydride and the like, with preference given topotassium phosphate.

As the palladium catalyst, organic acid salts of palladium, acetatessuch as Pd(OAc)₂ and the like, coordination compounds of palladium anddibenzylideneacetone and the like such as Pd(dba)₂ and Pd₂(dba)₃ and thelike, can be mentioned.

In addition, it is preferable to use the palladium catalyst in the formof a palladium complex using, as a ligand, organic phosphines such astri-t-butylphosphine (t-Bu₃P), dicyclohexylbiphenylphosphine(Cy₂biphen), triphenylphosphine (PPh₃) and the like or an iron complex(dppf) consisting of two molecules of cyclopentadienyldiphenylphosphineand one molecule of iron.

In this reaction, the amount to be used of the amino acid derivativerepresented by the formula (7) is not less than an equimolar amount,generally 1 to 3-fold equivalents, relative to the halogenated purinecompound represented by the formula (6), which is the other startingmaterial.

The amount of the base to be used is generally 0.1 to fold equivalents,preferably 1 to 5-fold equivalents, relative to the halogenated purinecompound represented by the formula (6), and the amount of the palladiumcatalyst to be used is generally 0.005 to 1-fold equivalent, preferably.0.01 to 0.2-fold equivalent, relative to the halogenated purinecompound. In addition, a phosphine ligand is used in an amount ofgenerally 0.005 to 1-fold equivalent, preferably 0.01 to 0.5-foldequivalent, relative to the halogenated purine compound.

The solvent is not particularly limited as long as it is inert to thereaction and exemplified by dimethylformamide, tetrahydrofuran, dioxane,toluene, benzene and the like. The amount of the solvent to be used isgenerally 1 to 100-fold weight, preferably 5 to 50-fold weight, relativeto the halogenated purine compound represented by the formula (6).

The reaction temperature at this time is optional as long as it is nothigher than the boiling point of the organic compound in the reactionsystem. It is generally 10-150° C., preferably 50-120° C., and thereaction time is generally 1-48 hours, preferably 2-24 hours.

The above-mentioned (purin-6-yl)amino acid represented by the formula(3) can be produced by reacting the above-mentioned halogenated purinecompound represented by the formula (6) with a halogenated amino acidderivative represented by the formula (8)

wherein R¹, R⁸, R⁹, X, Y and m are as defined above.

In both starting compounds represented by, the formulas (6) and (8),each substituent of R², R³, R⁴, R¹, R⁸ and R⁹ is required to have asubstituent corresponding to the substituent that the object(purin-6-yl)amino acid represented by the formula (3) has. For bothcompounds, the substituent X is particularly preferably iodine atom,from among halogen atoms such as chlorine atom, bromine atom, iodineatom and the like, from the aspect of reactivity.

In the above-mentioned reaction, a compound represented by the formula(6), which is a starting material, is as defined above, and as ahalogenated amino acid derivative represented by the formula (8), whichis the other starting material, benzyl(R,S)-2-[(t-butoxycarbonyl)amino]-3-iodopropanoate, benzyl(R,S)-2-[(t-ethoxycarbonyl)amino]-3-bromopropanoate and the like can bementioned.

Generally in this reaction, a halogenated amino acid derivativerepresented by the formula (8), which is a starting material, is reactedwith zinc (Zn) to give a zinc compound, wherein —X has been converted to—ZnX in the formula (8) (Step 1), and the reaction product is reactedwith a halogenated purine compound represented by the formula (6) (Step2).

The reaction of this Step 1 is carried out in the presence oftrialkylsilyl halide (e.g., as trimethylsilyl chloride etc.) in anorganic solvent.

The amount of zinc powder to be used is generally 3 to 15-foldequivalents, preferably 4 to 10-fold equivalents, relative to thehalogenated amino acid derivative, which is a starting material, and theamount of trialkylsilyl halide to be used is generally 0.01 to 1-foldequivalent, preferably 0.05 to 0.5-fold equivalent, relative to thehalogenated amino acid derivative.

For a solvent, dimethylformamide, tetrahydrofuran, dioxane and the likeare used. The amount of the solvent to be used is generally 1 to100-fold weight, preferably 5 to 50-fold weight, relative to thehalogenated amino acid derivative.

The reaction method generally includes dispersing a zinc powder andtrialkylsilyl halide in a solvent such as dimethylformamide and thelike, sonicating the mixture, adding thereto a solution of a halogenatedamino acid derivative represented by the formula (8) in a solvent suchas tetrahydrofuran, sonicating the mixture, and removing the remainingzinc powder.

The reaction temperature at this time is optional as long as it is nothigher than the boiling point of the organic compound in the reactionsystem. It is generally 10-150° C., and the reaction time is generally1-48 hours, preferably 2-24 hours.

The reaction of Step 2 is carried out by reacting the zinc compoundproduced in Step 1 with a halogenated purine compound represented by theformula (6) in a solvent in the presence of a palladium catalyst.

In this Step, as a solvent, the solvents similar to those used in Step 1can be mentioned, and as a palladium catalyst, the palladium catalystssimilar to those mentioned above are used.

The amount to be used of the halogenated amino acid derivativerepresented by the formula (8) is generally not less than an equimolaramount, preferably 1 to 3-fold equivalents, relative to the halogenatedpurine compound represented by the formula (6), which is the otherstarting material. The amount of the palladium catalyst to be used isgenerally 0.005 to 1-fold equivalent, preferably 0.01 to 0.2-foldequivalent, relative to the halogenated purine compound. In addition, aphosphine ligand is used in an amount of generally 0.005 to 1-foldequivalent, preferably 0.01 to 0.5-fold equivalent, relative to thehalogenated purine compound. The amount of the solvent to be used isgenerally 1 to 100-fold weight, preferably 5 to 50-fold weight, relativeto the halogenated purine compound.

The reaction method includes adding the above-mentioned halogenatedpurine compound represented by the formula (6), which is a startingmaterial, a palladium catalyst, and preferably a ligand similar to theabove-mentioned one to a solvent such as dimethylformamide, adding thisto the reaction solution after removing the zinc powder obtained in Step1, and stirring the mixture to allow for reaction.

The reaction temperature at this time is optional as long as it is nothigher than the boiling point of the organic compound in the reactionsystem. It is generally 10-150° C., and the reaction time is generally1-48 hours, preferably 2-24 hours.

Of the above-mentioned (purin-6-yl)amino acids represented by theformula (3), a compound represented by the formula (4), wherein (Y)_(m)is trimethylene, can be also produced by reacting the aforementionedhalogenated purine compound represented by the formula (6) with an aminoacid derivative represented by the following formula (9)

wherein R¹, R⁶ and R⁷ are as defined above.

As the amino acid derivative represented by the formula (9), which is astarting material, a compound having a substituent corresponding to theobject (purin-6-yl)amino acid represented by the formula (4) is used.For example, ethyl (R,S)-2-[(diphenylmethylidyne)amino]pent-4-enoate canbe mentioned.

In this reaction, the halogenated purine compound represented by theformula (6) is subjected to a coupling reaction with an amino acidderivative represented by the formula (9) by a well-known method to givea compound of the above-mentioned formula (3) wherein (Y)_(m) isethynylene, which compound is then hydrogenated to easily give(purin-6-yl)amino acid wherein (Y)_(m) is trimethylene.

The coupling reaction is usually carried out in a solvent in thepresence of a metal halide, a palladium catalyst and an organic base.

As the metal in the metal halide, copper is representative, and ashalogen, iodine atom is representative.

As the palladium catalyst, a catalyst similar to the above-mentioned oneis used, and as the organic base, organic amines, such as triethylamine,can be mentioned.

In this reaction, the amount to be used of the amino acid derivativerepresented by the formula (9) is not less than an equimolar amount,generally 1 to 3-fold equivalents, relative to the halogenated purinecompound represented by the formula (6), which is the other startingmaterial.

The amount of the metal halide to be used is generally 0.05 to 1-foldequivalent, preferably 0.08 to 0.5-fold equivalent, relative to thehalogenated purine compound represented by the formula (6). The amountof the palladium catalyst to be-used is generally 0.005 to 0.1-foldequivalent relative to the halogenated purine compound represented bythe formula (6).

As the solvent, dimethylformamide, tetrahydrofuran and the like areused. The amount of the solvent to be used is generally 1 to 100-foldweight, preferably 5 to 50-fold weight, relative to the halogenationpurine compound.

The reaction temperature at this time is optional as long as it is nothigher than the boiling point of the organic compound in the reactionsystem. It is generally 10-150° C., and the reaction time is generally1-48 hours, preferably 2-24 hours.

The hydrogenation reaction is carried out by reacting the couplingreaction product obtained by the above-mentioned reaction with hydrogenaccording to conventional hydrogenation reaction in the presence of acatalyst generally under pressurization.

As the catalyst here, for example, Pd/C and palladium chloridewell-known as hydrogenation catalysts can be mentioned. The amountthereof to be used is 0.05 to 0.5-fold weight relative to theabove-mentioned coupling reaction product.

While the solvent for the coupling reaction is not particularly limitedas long as it is inert to the reaction, alcohols such as methanol,ethanol and the like is preferably used. The amount of the solvent to beused is generally 1 to 100-fold weight, preferably 5 to 50-fold weight,relative to the above-mentioned coupling reaction product.

The reaction time is generally 1-48 hours, preferably 2-24 hours.

The above-mentioned (purin-6-yl)amino acid represented by the formula(5) can be produced by reacting the above-mentioned halogenated purinecompound represented by the formula (6) with an amino acid derivativerepresented by the following formula (10)

wherein R¹, R⁸, R⁹; Y and m are as defined above, W is —Sn(R⁵)₃, and R⁵is a lower alkyl group.

In the amino acid derivative represented by the formula (10), which is astarting material for this reaction, the substituent R⁵ is exemplifiedby methyl, ethyl, propyl and the like, and as the amino acid derivative,methyl(R,S)-2-[(t-butoxycarbonyl)amino]-3-[4-(trimethylstannanyl)phenyl]propionateand the like can be mentioned.

The reaction of a halogenated purine compound represented by the formula(6) with an amino acid derivative represented by the formula (10) isgenerally carried out in a solvent in the presence of a metal halide, apalladium catalyst and an arsenic compound.

Here, the metal halide and palladium catalyst are as defined above, andas the arsenic compound, trialkylarsine such as trimethylarsine,triphenylarsine and the like and triarylarsine can be mentioned.

In this reaction, the amount to be used of an amino acid derivativerepresented by the formula (10) is generally 1 to 3-fold equivalents,preferably 1.05 to 1.5-fold equivalents, relative to the halogenatedpurine compound represented by the formula (6).

The amount of the metal halide to be used is generally 0.05 to 1-foldequivalent, preferably 0.08 to 0.5-fold equivalent, relative to thehalogenated purine compound represented by the formula (6). The amountof the palladium catalyst to be used is generally 0.005 to 0.1-foldequivalent, and the amount of the arsenic compound to be used is 0.05 to0.5-fold equivalent, preferably 0.08 to 0.3-fold equivalent.

As the solvent, dimethylformamide, tetrahydrofuran and., the like areused. The amount of the solvent to be used is generally 1 to 100-foldweight, preferably 2 to 50-fold weight, relative to the halogenatedpurine compound.

The reaction temperature at this time is optional as long as it is nothigher than the boiling point of the organic compound in the reactionsystem. It is generally 10-100° C., and the reaction time is generally1-100 hours, preferably 2-50 hours.

After the completion of the reaction, a catalyst is removed according toconventional methods and then the solvent is removed according toconventional methods to isolate the object compound, after which thecompound is purified as necessary by an appropriate method to give theobject compound.

When the object compound is obtained as a free base, it can be convertedto the object salt by a method known per se or a method analogousthereto. When it is obtained as a salt, it can be converted to a freebase or other object salt by a method known per se or a method analogousthereto.

When the object compound has stereoisomers, they can be also isolated asdesired by appropriate separation and purification methods. When theobject compound is a racemate, it can be separated into an S form and anR form by conventional methods for optical resolution. Moreover, it isalso possible to produce the object compound in an S form or R formusing an (S)- or (R)-halogenated amino acid derivative as a startingmaterial. When the object compound has a stereoisomer, the presentinvention encompasses a single isomer and a mixture thereof.

The (purin-6-yl)amino acid represented by the formula (1) can be easilyproduced by such methods and the obtained (purin-6-yl)amino acid isuseful as a pharmaceutical product such as an anti-cancer agent, anantiviral agent and the like or a production intermediate therefor.

EXAMPLES

The present invention is be explained in more detail in the following byreferring to Examples. It is needless to say that these Examples are notintended to restrict the present invention.

Example 1-1 Production ofbenzyl(R,S)-3-(9-benzylpurin-6-yl)-2-[(tert-butoxycarbonyl)amino]propanoate

Dimethylformamide (DMF) (1 ml) containing zinc powder (380 mg, 6 mmol)dispersed therein was placed in a flask and the flask was purged with anargon gas. Thereto was added trimethylsilyl chloride. (80 μl, 0.6 mmol).This mixture was sonicated at room temperature for 30 min and then asolution of benzyl (R,S)-2-[(tert-butoxycarbonyl)amino]-3-iodopropanoate(405 mg, 1 mmol) in DMF (3 ml) was continuously added under an argonatmosphere, which was followed by sonication at room temperature for 40min. This was transferred into a solution of 9-benzyl-6-iodopurine (168mg, 0.5 mmol), Pd₂ dba₃ (17 mg, 0.02 mmol) and tri(o-tolyl)phosphine (23mg, 0.08 mmol) in DMF (2 ml).

The reaction mixture was stirred at room temperature for 5 hr and leftstanding overnight.

Thereafter, the solvent was evaporated under reduced pressure, and theresidue was diluted with ethyl acetate (70 ml) and washed twice withwater (60 ml each) and once with brine (60 ml).

The solvent was evaporated from the organic layer and the residue waspurified by silica gel column (ethyl acetate/hexane, 1:1) chromatographyto give benzyl(R,S)-3-(9-benzyl(purin-6-yl))-2-[(tert-butoxycarbonyl)amino]propanoate(216 mg, yield: 89%) as a colorless, amorphous solid.

Example 1-2 Production of benzyl(R,S)-3-(9-benzylpurin-6-yl)-2-[(tert-butoxycarbonyl)amino]propanoate

Trimethylsilyl chloride (160 μl, 1.3 mmol) was added through septum- toan argon purged flask containing a suspension of zinc powder (2.8 g, 43mmol) in DMF (4 ml). The mixture was sonicated at room temperature for20 min. Then a solution of benzyl(R,S)-2-[(tert-butoxycarbonyl)amino]-3-iodopropanoate (2.9 g, 7.2 mmol)in DMF (22 ml) prepared under argon was added through septum to thesuspension of activated Zn and the sonication was continued for another40 min at room temperature, after which zinc was allowed to settle. Thesupernatant was transferred through septum to a mixture of9-benzyl-6-iodopurine (1.35 g, 4.0 mmol), Pd₂ dba₃ (104 mg, 0.12 mmol)and tri(o-tolyl)phosphine (146 mg, 0.48 mmol) in DMF (16 ml) preparedunder argon. The reaction mixture was stirred at room temperature for 8hr and allowed to stay overnight and then the solvent was evaporated invacuo. The residue was diluted with ethyl acetate (70 ml) and washedwith water (2×60 ml) and brine (60 ml). The organic phase was evaporatedand the residue was chromatographed on a silica gel column (ethylacetate/hexane, 1:1) to give the title compound (1.85 g, yield 95%) as acolorless, amorphous solid.

MS (FAB): 488 (6, M+1); 432 (5); 252 (8); 225-(9); 147 (14); 91 (Bn).

HRMS (FAB): for C₂₇H₃₀N₅O₄ calculated 488.2298; found 488.2290.

¹H NMR (500 MHz, CDCl₃): 1.40 (s, 9H, 3×CH₃-Boc); 3.62 (dd, 1H, J=4.6and 15.8, CH_(A) H _(B)CH); 3.89 (dd, 1H, J=5.7 and 15.8, CH_(A)H_(B)CH); 4.98 (m, 1H, CHCO); 5.09 (dd, 2H, J=11.9 and 38.7, OCH₂Ph); 5.40 (s, 2H, NCH ₂Ph); 6.16 (d, 1H, J=8.5, NH); 7.20-7.38 (m, 10H,arom.); 7.97 (s, 1H, H-8); 8.80 (s, 1H, H-2).

¹³C NMR (125.8 MHz, CDCl₃): 28.25 (CH₃); 34.58 (Pu—CH₂); 47.26 (NCH₂Ph);51.73 (CHCO); 66.93 (OCH₂Ph); 79.71 (C(CH₃)₃); 127.86, 128.00, 128.04,128.26, 128.62 and 129.13 (CH-arom.); 132.69. (C-5); 134.96 and 135.44(C-arom.); 143.90 (CH-8); 150.75 (C-4); 152.19 (CH-2); 155.53 (CO-Boc);157.72 (C-6); 171.57 (COOBn).

IR (CHCl₃): 3436, 3096, 3033, 3011, 2983, 1744, 1710, 1598, 1499, 1456,1406, 1368, 1334, 1230, 1193, 1163, 1057, 1028.

Example 2-1 Production ofmethyl(R,S)-3-[4-(9-benzylpurin-6-yl)phenyl]-2-[(tert-butoxycarbonyl)amino]propanoate

DMF (15 ml) was added to a flask containing 9-benzyl-6-iodopurine (547mg, 1.65 mmol),methyl(R,S)-2-[(tert-butoxycarbonyl)amino]-3-[4-(trimethylstannanyl)phenyl]propionate(827 mg, 1.87 mmol), Pd₂ dba₃ (92 mg, 0.1 mmol), triphenylarsine (AsPh₃)(61 mg, 0.2 mmol) and copper iodide (CuI)(76 mg, 0.4 mmol) under anargon atmosphere, and the mixture was stirred at 80° C. for 30 hr.

The solvent was evaporated under reduced pressure from the reactionmixture and the residue was dissolved in ethyl acetate. The ethylacetate solution was washed with water (80 ml) and brine (80 ml).

The solvent was evaporated from the organic layer and the residue waspurified by silica gel column (ethyl acetate/hexane, 1:2) chromatographyto give a crude product. This was recrystallized from ethylacetate/hexane to give the title compound (360 mg, yield: 45%) as whitecrystals.

Example 2-2 Production of methyl(R,S)-3-[4-(9-benzylpurin-6-yl)phenyl]-2-[(tert-butoxycarbonyl)amino]propanoate

DMF (15 ml) was added through septum to an argon purged flask containing9-benzyl-6-iodopurine (547 mg, 1.65 mmol), methyl(R,S)-2-[(tert-butoxycarbonyl)amino]-3-[4-(trimethylstannanyl)phenyl]propionate(827 mg, 1.87 mmol); Pd₂ dba₃ (92 mg, 0.1 mmol), AsPh₃ (61 mg, 0.2 mmol)and CuI (125 mg, 0.66 mmol). The mixture was stirred at 80° C. for 24hr. The solvent was evaporated in vacuo, the residue was dissolved inethyl acetate (80 ml) and washed with water (80 ml), filtrated andwashed with brine (80 ml). The organic phase was evaporated and theresidue was chromatographed on a silica gel 1 column (ethylacetate/hexane, 1:2) and recrystallized from ethyl acetate/heptane togive the title compound (440 mg, yield 55%) as white crystals.

m.p. 133-136° C.

MS (FAB): 488 (6, M+1); 432 (18); 337 (6); 300 (8); 91 (100, Bn).

HRMS (FAB): for C₂₇H₃₀N₅O₄ calculated 488.2298, found 488.2309.

¹H NMR (500 MHz, CDCl₃): 1.43 (s, 9H, 3×CH₃-Boc); 3.19 (m, 2H, CH ₂CH);3.72 (s, 3H, OCH₃); 4.65 (dd, 1H, J=13.4 and 5.6, CHNH); 5.05 (d, 1H,J=8.7, NH); 5.48 (s, 2H, CH ₂Ph); 7.31-7.37 (m, 7H, arom.); 8.10 (s, 1H,H-8); 8.74 (d, 2H, J(CH-arom., CH-arom.)=8.3, 2×CH-arom.); 9.04 (s, la,H-2). ¹³C NMR (125.8 MHz, CDCl₃): 28.26 ((CH₃)₃); 38.13 (CH₂CH); 47.23(CH₂Ph); 52.23 (OCH₃); 54.27 (CHNH); 79.95 (C(CH₃)₃); 127.76, 128.54,129.11, 129.63 and 129.91 (5×CH-arom.); 130.80 (C-5); 134.47(C-1-arom.); 135.15 (C-1-Ph); 139.20 (C-p-arom.); 144.06 (CH-8); 152.49(C-4); 152.55 (CH-2); 154.47 (C-6); 155.05 (COO from Boc); 172.07(COOMe).

IR (CHCl₃): 3438, 1743, 1710, 1583, 1561, 1498, 1450, 1249, 1165, 1063.

Anal. calculated for C₂₇H₂₉N₅O₄ (487.6): C, 66.51%; H, 6.00%; N, 14.36%;found: C, 66.52%; H, 5,94%; N, 14.23%

Example 3 Production of ethyl(R,S)-2-[(diphenylmethylidene)amino]-5-(9benzylpurin-6-yl)pent-4-ynoate

DMF (20 ml) and Et₃N were added through septum to an argon purged flaskcontaining 9-benzyl-6-iodopurine (3.03 g, 9 mmol), ethyl(R,S)-2-[(diphenylmethylidene) amino]pent-4-ynoate (3.57 g, 11.7 mmol),CuI (200 mg, 1.05 mmol) and Pd(PPh₃)₄ (300 mg, 0.26 mmol). The mixturewas stirred at 65° C. for 7 hr. The solvent was evaporated in vacuo andisolated by column chromatography on silica gel (ethyl acetate/hexane,4:3) to give the title compound (3.85 g, 83%) as a yellowish amorphoussolid.

MS (EI): 513 (6, M); 440 (33); 436 (35, M-Ph); 426 (14); 333 (12,M-N═CPh₂); 266 (7); 193 (15); 180 (9); 165 (18); 104 (6); 91 (100, Bn).

HRMS (EI): for C₃₂H₂₇N₅O₂ calculated 513.2165, found 513.2192.

¹H NMR (500 MHz, CDCl₃): 1.27 (t, 3H, J(CH₃, CH₂)=7.1, CH₃); 3.18 (dd,1H, J=17.1 and 8.5, CHAHBC≡C); 3.32 (dd, 1H, J=17.1 and 4.9, CH_(A)H_(B)C≡C); 4.14-4.27 (m, 2H, CH ₂CH₃); 4.49. (dd, 1H, J=8.5 and 4.9,CHCO); 5.41 (s, 2H, CH ₂Ph); 7.26-7.43 (m, 13H, arom.); 7.67 (d, 2H,J=7.4, arom.); 8.01 (s, 1H, H-8); 8.90 (S, 1H, H-2).

¹³C NMR (125.8 MHz, CDCl₃): 14.01, (CH₃); 24.65 (CH₂C≡C); 47.29 (CH₂Ph);61.39 (OCH₂); 63.86 (CHCO); 77.60 (C≡C—Pu); 97.42 (CH₂—C≡C); 127.79,127.92, 128.31, 128.45, 128.63, 128.65, 129.03, 129.14 and 130.37(CH-arom.); 134.27 (C-5); 135.97 and 139.40 (C-arom.); 142.00 (C-6);144.68 (CH-8); 151.47 (C-4); 152.63. (CH-2); 170.27 (COO); 172.35(CH-Ph₂) IR (CHCl₃): 2238, 1734, 1624, 1583, 1498, 1447, 1329, 1240,1195.

Example 4 Production of ethyl(R,S)-2-amino-5-(9-benzylpurin-6-yl)pentanoate

Ethyl(R,S)-2-[(diphenylmethylidene)amino]-5-(9-benzylpurin-6-yl)pent-4-ynoate(650 mg, 1.27 mmol) obtained in Example 3 in ethanol (80 ml) washydrogenated under slight overpressure in the presence of Pd/C catalyst(10 wt %, 80 mg). PdCl₂ (10% solution in 1 M aq. HCl, 100 μl) was addedthrough septum after 15 min and the hydrogenation was continued for 10hr (the progress was monitored by TLC). The catalyst was filtered offthrough Celite pad and the filtrate was evaporated in vacuo. The residuewas chromatographed on a silica gel column (ethyl acetate/methanol, 19:1to 9:1) to give the title compound (250 mg, 56%) as a brown amorphoussolid.

MS (FAB): 354 (21, M+1); 237 (14); 149 (17); 91 (100, Bn).

¹H NMR (200 MHz, CDCl₃): 8.91 (s, 1H, H-2); 8.04 (s, 1H, H-8); 7.36-7.29(m, 5H, arom.); 5.44 (s, 2H, CH ₂Ph); 4.16 (q, 2H, J(CH₂, CH₃)=7.1,OCH₂); 3.58 (br t, 1H, J=6.2, CHNH); 3.25 (t, 2H, J=7.2, Pu—CH ₂CH₂);3.00 (br, 2H, NH₂); 2.09-1.68 (m, 4H, 2×CH₂); 1.24 (t, 3H, J(CH₃,CH₂)=7.1, CH₃).

Example 5 Production of ethyl(R,S)-2-amino-5-(9-benzylpurin-6-yl)pent-4-ynoate

20% Aqueous citric acid (9 ml) was added to a solution of ethyl(R,S)-2-[(diphenylmethylidene)amino]-5-(9-benzylpurin-6-yl)pent-4-ynoate(752 mg, 1.47 mmol) obtained in Example 3 in THF (18 ml) and the mixturewas stirred at ambient temperature for 1 h. Then the reaction mixturewas diluted with water (70 ml) and washed with ethyl acetate (2×70 ml).To the water phase was added a saturated solution of NaHCO₃ (20 ml) tomake pH basic, then the solution was washed with ethyl acetate (2×60 ml)and the obtained organic phase was evaporated. The residue waschromatographed on a silica gel column (ethyl acetate/methanol, 17:3) togive the product (328 mg, 64%) as a yellow amorphous solid.

MS (EI): 349 (3, M); 347 (3); 276 (41, M−COOEt); 248 (100,M−glycinyl+H); 223 (9); 158 (8); 91 (95, Bn).

HRMS (EI): for C₁₉H₁₉N₅O₂ calculated 349.1539, found 349:1544

¹H NMR (200 MHz, CDCl₃): 8.94 (s, 1H, H-2); 8.07 (s, 1H, H-8); 7.39-7.27(m, 5H, arom.); 5.45 (s, 2H, CH ₂Ph); 4.24 (q, 2H, J(OCH₂, CH₃)=7.1,OCH₂); 3.82 (m, 1H, CH—NH₂); 3.10 (dd, IR, J=17.1 and 4.9, CH_(A)H_(B)C≡C); 2.95 (dd, 1H, J 17.1 and 7.4, CH_(A) H _(B)C≡C); 1.94 (brs, 2H, NH₂); 1.29 (t, 3H, J(CH₃, OCH₂) 7.1, CH₃).

¹³C NMR (50.3 MHz, CDCl₃): 173.35 (CO); 152.68 (CH-2); 151.53 (C-4);144.98 (CH-8); 141.72 (C-6); 134.81 (C-5); 134.46 (C-arom.); 129.17 (2C,CH-arom.); 128.68 (CH-arom.); 127.80 (2C, CH-arom.); 96.09 (CH₂—C≡C);78.36 (C≡C—Pu); 61.41 (OCH₂); 53.26 (CH—NH₂); 47.35 (CHH₂Ph); 26.55(CH₂—C≡); 14.14 (CH₃). IR (CHCl₃): 3387, 2239, 1735, 1621, 1584, 1404,1242, 1197.

Example 6 Production of (R,S)-9-benzyl-6-[(diphenylmethylideneamino)(ethoxycarbonyl)methyl]purine

Toluene was added to a flask containing 9-benzyl-6-iodopurine (1 mmol),ethyl [(diphenylmethylidene)amino]acetate (374 mg, 1.28 mmol), potassiumphosphate (2 mmol) as a base, Pd(OAc)₂ (22 mg, 0.1 mmol) andtri-t-butylphosphine (0.2 mmol) as a phosphine ligand under an argonatmosphere, and the mixture was stirred at 100° C. for 10 hr.

After the completion of the reaction, the solvent was evaporated and theresidue was purified by silica gel column (ethyl acetate/hexane,1:2-5:1) chromatography to give(R,S)-9-benzyl-6-[(diphenylmethylideneamino)(ethoxycarbonyl)methyl]purine as colorless crystals (yield: 32%).

m.p.: 189-192° C.

MS (FAB): 476

HRMS (EI): for C₂₉H₂₆N₅O₂ calculated 476.2087, found 476.2068. ¹H NMR(500 MHz, CDCl₃): 1.17 (t, 3H, J=7.1, CH ₃CH₂); 4.20 (d, 2H, J=7.1, CH₃CH ₂); 5.40 (d, 1H, J_(gem)=≈15.1, CH₂Ph-a), 5.45 (d, 1H, J_(gem)=15.1,CH₂Ph-b); 6.01 (s, 1H, COCHN); 7.26-7.44 (m, 13H, H-arom.); 7.71 (d, 2H,J=7.5, H-arom.); 8.00 (s, 1H, H-8); 9.01 (s, 1H, H-2)

¹³C NMR (100.6 MHz, CDCl₃): 14.05 (CH₃); 47.29 (CH₂Ph); 61.54 (CH₂CH₃);67.62 (COCHN); 127.90, 127.95, 128.55, 128.58, 128.81, 129.11, 129.25,130.51 (CH-arom.); 132.22, 135.08, 136.10, 139.42 (C-5, C-1-arom.);144.34 (CH-8); 151.94 (C-4); 152.69 (CH-2); 157.33 (C-6); 169.27 (C═O);172.75 (C═N)

Example 7 to 11 Production of(R,S)-9-benzyl-6-[(diphenylmethylideneamino)(ethoxycarbonyl)methyl]purine

A solvent shown in Table 1 was added to a flask containing9-benzyl-6-iodopurine (1 mmol), ethyl[(diphenylmethylidene)amino]acetate (374 mg, 1.28 nmol), a base (2 mmol)shown in Table 1, Pd(OAc)₂ (22 mg, 0.1 mmol) and tri-t-butylphosphine(0.2 mmol) as a phosphine ligand shown in Table 1 (0.2 mmol for1-coordinate ligand and 0.1 mmol for 2-coordinate ligand) under an argonatmosphere, and the mixture was stirred at 100° C. for the reaction timeas shown in Table 1. After the completion of the reaction, the reactionmixture was treated in the same manner as in Example 6 to give(R,S)-9-benzyl-6-[(diphenylmethylideneamino)(ethoxycarbonyl)methyl]purineas colorless crystals in a yield shown in Table 1. TABLE 1 reactionyield No. ligand base solvent time (hr) (%) 7 Cy₂Pbiphen K₃PO₄ toluene28 16 8 Cy₂Pbiphen K₃PO₄ dioxane 14 37 9 dppf K₃PO₄ dioxane 14 32 10Cy₂Pbiphen NaH toluene 28 7 11 Cy₂Pbiphen K₃PO₄ DMF 8 55

Example 12 Production of 6-[(R,S)-(diphenylmethylideneamino)(ethoxycarbonyl)methyl]-9-[(R,S)-(tetrahydropyran-2-yl)]purine

The reaction under the same conditions as in Example 11 except that9-(tetrahydropyran-2-yl)-6-iodopurine (1 mmol) was used instead of9-benzyl-6-iodopurine (1 mmol), followed by working up gave 6-[(R,S)(diphenylmethylideneamino)(ethoxycarbonyl)methyl]-9-[(R,S)-(tetrahydropyran-2-yl)]purine as ayellow amorphous solid (yield 63s).

MS (FAB): 470

HRMS (EI): for C₂₉H₂₈N₅O₃ calculated 470.2192, found 470.2178.

¹H NMR (400 MHz, CDCl₃): 1.16 (t, 3H, J=7.1, CH ₃CH₂); 1.64-2.15 (m, 6H,CH₂-THP); 3.79, (brt, 1H, J=10.8, CH₂-Oa); 4.16-4.22 (m, 3H, CH ₂CH₃,CH₂-Ob); 5.80 (d, 1H, J=9.8, OCHN); 5.98, 6.00 (2×s, 2×½H, NCHCO);7.26-7.72 (m, 10H, H-arom); 8.25 (9, 1H, H-8); 8.98 (s, 1H, H-2)

¹³C NMR (100.6 MHz, CDCl₃): 14.04 (CH₃CH₂); 22.75, 24.83, 31.74(CH₂-THP); 61.59. (CH₂CH₃); 67.66 (COCHN); 68.81 (CH₂—O); 81.95 (NCHO);127.90, 128.24, 128.58, 128.85, 129.26, 130.53 (CH-arom.); 132.22,136.04, 139.37 (C-5, C-1-arom.); 142.35 (CH-8); 151.09 (C-4); 152.50(CH-2); 157.31 (C-6); 169.23 (C═O); 172.79 (C═N)

IR (CHCl₃); 1743, 1653, 1623, 1597, 1495, 1447, 1333

Example 13 Production of 6-[(R,S)-(diphenylmethylideneamino)(ethoxycarbonyl)methyl]-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purine

The reaction under the same conditions as in Example 11 except that9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-6-iodopurine (1 mmol) was usedinstead of 9-benzyl-6-iodopurine (1 mmol), followed by working up gave6-[(R,S)-(diphenylmethylideneamino)(ethoxycarbonyl)methyl]-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purineas a yellow amorphous solid (yield 31%).

MS (FAB): 644 (20) [M+H], 386 (32), 312 (35), 139 (100)

HRMS (FAB): for C₃₃H₃₄N₅O₉ [M+H] calculated 644.2357, found 644.2351.

Anal. calculated for C₃₃H₃₃N₅O₉ (643.6): C, 61.58%; H, 5.17%; N, 10.88%;found: C, 61.47%; H, 5.40%; N, 10.50%.

¹H NMR (500 MHz, CDCl₃): 1.18 (t, 3H, J=7.1, CH ₃CH₂); 20.9, 2.11, 2.15(3×s, 3×3H, CH ₃CO); 4.22 (d, 2H, J=7.1, CH₃ CH ₂); 4.37-4.48 (m, 3H,H-4′, H-5′); 5.69 (brm, 1H, H-3′); 5.96-6.00 (m, 2H, H-2′, COCHN); 6.25(d, 1H, J=5.2, H-1′); 7.26-7.71 (m, 10H, H-arom.); 8.17 (s, 1H, H-8);8.99 (s, 1H, H-2)

¹³C NMR (100.6 MHz, CDCl₃): 14.05 (CH₃CH₂); 20.36, 20.49, 20.72 (CH₃CO);61.68 (CH₂CH₃); 63.00, 63.05 (CH₂-5′); 67.74, 67.81 (COCHN); 70.59,70.62 (CH-3′); 72.96, 73.03 (CH-2′); 80.40 (CH-4′); 86.25, 86.30(CH-1′); 127.86, 127.94, 128.60, 128.89, 129.24, 130.60 (CH-arom.);132.94, 135.98, 139.30, (C-5, C-1-arom.); 142.88 (CH-8); 151.41 (C-4);152.76 (CH-2); 157.85 (C-6); 169.10, 169.30, 169.53, 170.28 (C═O);173.00 (C═N) IR (CHCl₃); 1749, 1654, 1617, 1595, 1497, 1408, 1370, 1333,1238

Example 14 Production of benzyl(R,S)-3-[9-(tetrahydropyran-2-yl)purin-6-yl]-2-[(tert-butoxycarbonyl)amino]propanoate

The reaction under the same conditions as in Example 1-2 except that6-iodo-9-(tetrahydropyran-2-yl)purine: (1.5 g, 4.5 mmol) was usedinstead of 9-benzyl-6-iodopurine (1.35 g, 4.0 mmol) of Example 1-2,followed by working up gave the title compound (1.92 g, yield 88%) aswhite crystals.

m.p. 101-103° C.

MS (EI): 481 (1, M); 397 (3, M-THP+H); 346 (10, M-COOBn); 262 (17); 218(10), 206 (28); 188 (20); 162 (100); 134 (54); 91 (66, Bn).

HRMS (EI): for C₂₅H₃₁N₅O₅ calculated 481.2325; found 481.2323.

¹H NMR (500 MHz, CDCl₃): 1.41 (s, 9H, 3×CH₃-Boc); 1.67-1.87 (m, 3H, CH₂from THP); 2.03-2.15 (m, 3H, CH₂ from THP); 3.62 (dd, 1H, J=4.6 and16.4, CH _(A)H_(B) from alanyl); 3.79 (m, 1H, H-5′); 3.90 (dd, 1H, J=5.5and 16.4, CH_(A) H _(B) from alanyl); 4.19 (m, 1H, H-5′); 4.97 (m, 1H,CHNH); 5.10 (m, 2H, CH ₂Ph); 5.77. (d, 1H, J=10.5, H-1′); 6.10 (m, 1H,NH); 7.24 (m, 5H, arom.); 8.22 (s, 1H, H-8); 8.77 (s, 1H, H-2).

¹³C NMR (125.8 MHz, CDCl₃): 22.74 (CH₂-THP); 24.84 (CH₂-THP); 28.29(CH₃-tBu); 31.79 (CH₂-THP); 34.53 (CH ₂ from alanyl); 51.79 (CH fromalanyl); 66.99 (CH ₂Ph); 68.83 (CH₂-5′); 79.75 (C-tBu); 81.98 (CH-1′);128.07, 128.10 and 128.32 (3×CH-arom.) 132.95 (C-5); 135.49 (C-arom.);141.92 (CH-8); 149.98 (C-4); 152.05 (CH-2); 155.54 (CO-Boc); 157.80(C-6); 171.60 (COOBn). IR (CHCl₃): 3436, 2983, 2867, 1735, 1710, 1599,1584, 1498, 1456, 1369, 1335, 1250, 1163, 1086, 1046, 913.

Anal. calculated for C₂₃H₃₁N₅O₅ (481.5): C, 62.36%; H, 6.49%; N, 14.54%;found: C, 62.04%; H, 6.79%; N, 14.13%.

Example 15 Production of benzyl(R,S)-3-[9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purin-6-yl]-2-[(tert-butoxycarbonyl)amino]propanoate

The reaction under the same conditions as in Example 1-2 except that6-iodo-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purine (2.02 g, 4 mmol)was used instead of 9-benzyl-6-iodopurine (1.35 g, 4.0 nmol) of Example1-2, followed by working up gave the title compound (1.96 g, yield 75%)as a yellow amorphous solid.

MS (FAB): 656 (47, M+1); 600 (25); 342 (100); 298 (35); 281 (66).

HRMS (FAB): for. C₃₁H₃₈N₅O₁₁ calculated 656.2568; found 656.2549.

¹H NMR (500 MHz, CDCl₃): 1.43 (s, 9H, 3×CH₃-Boc); 2.10 (s, 3H, CH₃);2,14 (s, 3H, CH₃); 2.18 (s, 3H, CH₃); 3.65 (ddd, 1H, J=4.6, 13.4 and15.9, CH _(A)H_(B) from alanyl); 3.90 (td, 1H, J=6.0 and 16.0, CH_(A) H_(B) from alanyl); 4.38-4.51 (m, 3H, H-4′+H-5′) 5.00 (m, 1H, CH fromalanyl); 5.07-5.17 (m, 2H, CH₂Ph); 5.69 (dd, 1H, J=4.5 and 9.7, H-3′);5.97 (m, 1H, H-2′); 6.07 (br t, 1H, J=7.2, NH); 6.24 (t, 1H, J=5.4,H-1′); 7.26 (m, 5H, arom.); 8.177 and 8.184 (2×s, 1H, H-8); 8.78 and8.79 (2×s, 1H, H-2).

¹³C NMR (125.8 MHz, CDCl₃): 20.38, 20.48 and 20.70 (3×CH₃CO) 28.23 (CH₃.tBu); 34.47 and 34.59 (CH₂ from alanyl); 51.61 and 51.66 (CH fromalanyl); 62.98 (CH₂-5′); 67.03 (CH₂Ph); 70.53 (CH-3′); 72.92 and 73.05(CH-2′); 79.80 (C-tBu); 80.32 (CH-4′); 86.33 and 86.41 (CH-1′); 128.12and 128.30 (CH-arom.); 133.42 and 133.48 (C-5); 135.35 (C-arom.); 142.42and 142.53 (CH-8); 150.21 and 150.24 (C-4); 152.25 (CH-2); 155.48 (CO,Boc); 158.32 (C-6); 169.28, 169.51 and 170.24 (3×COCH₃); 171.48 (COOBn).

IR (CDCl₃): 3436, 3029, 3011, 2983, 1749, 1711, 1599, 1498, 1456, 1399,1336, 1235, 1205, 1163, 1097, 1050, 911, 645, 698.

Anal. calculated for C₃₁H₃₇N₅O₁₁ (655.6): C, 56.79%; H, 5.69%; N,10.68%; found: C, 57.06%; H, 6.04%; N, 10.22%.

Reference Example 19-(3,5-di-O-β-toluyl-β-D-2′-deoxyribofuranosyl)-6-iodopurine whitecrystals, m.p. 139-140° C.

MS (FAB): 599 (6, M+1); 353 (6); 247 (19); 185 (10); 119 (82); 91 (38);81 (100).

HRMS (FAB): for C₂₆H₂₄₁N₄O₅ calculated 599.0791; found 599.0787.

¹H NMR (500 MHz, CDCl₃): 2.41 (s, 3H, CH₃); 2.45 (s, 3H, CH₃) 2.89 (ddd,1H, J=2.2, 5,9 and 14.2, H-2′a); 3.19 (ddd, 1H, J=6.4, 7.9 and 14.3,H-2′b); 4.66 (m, 2H, H-4′+H-5′a); 4.79 (m, 1H, H-5′); 5.84 (m, 1H,H-3′); 6.55 (dd, 1H, J=5.9 and 8.1, H-1′); 7.2.1 (d, 2H, J=8.0, arom.);7.28 (d, 2H, J=8.0, arom.); 7.85 (d, 2H, J=8.2, arom.); 7.97 (d, 2H, J8.2, arom.); 8.30 (s, 1H, H-8); 8.55 (s, 1H, H-2).

¹³C NMR (100 MHz, CDCl₃): 21.69 (CH₃); 21.72 (CH₃); 37.90 (CH₂-2′);63,74 (CH₂-5′); 74.99 (CH-3′); 83.41 (CH-4′); 85.44 (CH-1′); 122.42(C-6); 126.30 and 126.48 (2×C-1-arom.); 129.29, 129.55 and 129.80(3×CH-arom.); 139.22 (C-5); 142.50 (CH-8); 144.26 and 144.61(2×C-4-arom.); 147.33 (C-4); 151.94 (CH-2); 165.90 and 166.05 (2×CO).

IR (CDCl₃): 3033, 3003, 1721, 1612, 1581, 1554, 1485, 1429, 1333, 1269,1178, 1102, 1021, 914, 839, 691.

Anal. calculated for C₂₆H₂₃₁N₄O₅ (598.4): C, 52.19%; H, 3.87%, I 21.21%;N, 9.36%; found: C, 52.27%; H, 4.00%; I, 21.17%; N, 9.26%.

Example 16 Production of benzyl(R,S)-3-[9-(3,5-di-O-p-toluyl-β-D-2′-deoxyribofuranosyl)purin-6-yl]-2-[(tert-butoxycarbonyl)amino]propanoate

The reaction under the same conditions as in Example 1-2 except that9-(3,5-di-O-p-toluyl-β-D-2′-deoxyribofuranosyl)-6-iodopurine (1.88 g,3.14 mmol) in Reference Example 1 was used instead of9-benzyl-6-iodopurine (1.35 g, 4.0 mmol) of Example 1-2, followed byworking up gave the title compound (2.22 g, yield 94%) as a yellowamorphous solid.

MS (FAB): 750 (10, M+1); 398 (18); 342 (100); 321 (56); 298 (36); 281(66); 252 (25).

HRMS (FAB): for C₄₁H₄₃N₅O₉ calculated 750.3139; found 750.3140.

¹H NMR (500 MHz, CDCl₃): 1.43 (s, 9H, tBu); 2.43 and 2.47 (2×s, 6H,2×CH₃ from toluyl); 2.83 (m, 1H, H-2′); 3.15 (m, 1H, H-2′); 3.59 (m, 1H,CH_(A) H _(B) from alanyl); 3.87 (dt, 1H, J=5.5 and 14.7, CH _(A)H_(B)from alanyl); 4.65-4.70 (m, 2H, H-4′+H-5′); 4.75-4.80 (m, 1H, H-5′);4.99 (m, 1H, CH from alanyl); 5.10 (m, 2H, CH₂Bn); 5.85 (m, 1H, H-3′);6.08 (2×d, 1H, J=8.7, NH); 6.59 (dd, 1H, J=6.0 and 8.0); 7.21-7.32 (m,9H, arom.); 7.94 (dd, 2H, J=3.7 and 8.2, arom.); 8.00 (d, 2H, J=8.2,arom.); 8.20 (s, 1H, H-8); 8.74 and 8.75 (2×s, 1H, H-2).

¹³C NMR (125.8 MHz, CDCl₃): 21.69 and 21.75 (2×CH₃ from toluyl); 28.29(C(CH ₃)₃); 34.52 and 34.63 (CH₂ from alanyl); 37.76 and 37.84 (CH₂-2′);51.74 (CH from alanyl); 63.97 (CH₂-5′); 67.03 and 67.05 (CH₂Ph); 75.06(CH-3′); 79.81 (CC(CH₃)₃); 83.08 and 83.11 (CH-4′); 84.79 (CH-1′);126.35 and 126.62 (2×C-p-arom.); 128.13, 128.33, 129.31, 129.64 and129.82 (5×CH-arom.); 133.47 (C-5); 135.40 (C-i-arom.); 142.32 (CH-8);144.23 and 144.59 (2×C-i-arom.); 150.21 (C-4); 152.09 (CH-2); 155.55 (COfrom Boc); 158.10 (C-6); 165.94 and 166.16 (CO from toluyl); 171.52(COOBn).

IR (CDCl₃): 3435, 3020, 2983, 1719, 1612, 1599, 1498, 1456, 1369, 1335,1269, 1179, 1163, 1102, 1021.

Anal. calculated for C₄₁H₄₃N₅O₉ (749.8): C, 65.68%; H, 5.78%; N, 9.34%;found: C, 65.80%; H, 6.06%; N, 8.93%.

Example 17 Production of benzyl(R,S)-3-[9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purin-6-yl]-2-[(benzyloxycarbonyl)amino]propanoate

The reaction in the same manner as in Example 1-2 gave the titlecompound.

¹H NMR (500 MHz, CDCl₃): 2.08 (s, 3H, CH₃); 2,11 (s, 3H, CH₃); 2.16 (s,3H, CH₃); 3.66 (td, 1H, J=4.4 and 15.6, CH _(A)H_(B) from alanyl); 3.93(td, 1H, J=5.6 and 16.0, CH_(A) H _(B) from alanyl); 4.36-4.48. (m, 3H,H-4′+H-5′); 5.05 (m, 1H, CH from alanyl); 5.10 (s, 2H, CH₂Ph); 5.12 (s,2H, CH₂Ph); 5.66 (m, 1H, H-3′); 5.94 (dt, 1H, J=5.4 and 17.5H-2′); 6.21(t, 1H, J=5.5, H-1′); 6.45 (m, 1H, NH); 7.20-7.34 (m, 10H, arom.); 8.166and 8.173 (2×s, 1H, H-8); 8.72 and 8.74 (2×s, 1H, H-2).

¹³C NMR (125.8, MHz, CDCl₃): 20.32, 20.46 and 20.67 (3×CH₃CO); 34.30 and34.42 (CH₂ from alanyl); 52.12 (CH from alanyl); 62.98 (CH₂-5′); 66.93and 67.03 (2×CH ₂Ph); 70.55 (CH-3′); 72.98 and 73.11 (CH-2′); 80.38(CH-4′); 86.38 and 86.46 (CH-1′); 128.04, 128.18, 128.36 and 128.43(CH-arom.); 133.23 and 133.29 (C-5); 135.31 and 136.31 (2×C-arom.);142.55 and 142.66 (CH-8); 150.30 (C-4); 152.25 (CH-2); 156.10 (NCO);158.07 (C-6); 169.26, 169.49 and 170.23 (3×COCH₃); 171.08 (COOBn).

IR (CDCl₃): 3430, 3030, 3013, 1750, 1599, 1500, 1456, 1410, 1375, 1336,1229, 909, 645, 603.

Example 18 Production of benzyl(R,S)-3-[9-(3,5-di-O-p-toluyl-β-D-2′-deoxyribofuranosyl)purin-6-yl]-2-[(benzyloxycarbonyl)amino]propanoate

The reaction in the same manner as in Example 1-2 gave the titlecompound as a yellowish amorphous solid.

MS (FAB): 784 (8, M+1); 432 (23); 321 (8); 281 (11); 154 (21); 119 (82);91 (100%).

HRMS (FAB): for C₄₄H₄₂N₅O₉ calculated 784.2983; found 784.2955.

¹H NMR (500 MHz, CDCl₃): 2.40 (s, 3H, CH₃); 2.45 (s, 3H, CH₃) 2.83 (dm,1H, J=14.2, H-2′); 3.15 (m, 1H, H-2′); 3.63 (ddd, 1H, J=4.4, 16.0 and25.2, CH _(A)H_(B) from alanyl); 3.93 (ddd, 1H, J=5.6, 14.0 and 15.8,CH_(A) H _(B) from alanyl); 4.67 (m, 1H, H-4′); 4.68 (m, 1H, H-5′); 4.77(m, 1H, H-5′); 5;06 (m, 1H, CH from alanyl); 5.10 (s, 1H, CH ₂Ph); 5.11(s, 1H, CH ₂Ph); 5.83 (br d, 1H, J=4.7, H-3′); 6.49 (dd, 1H, J=8.8 and15.4, NH); 6.56 (t, 1H, J=6.6, H-1′); 7.18-7.34 (m, 14H, arom.); 7.92(dd, 2H, J=4.7 and 7.8, arom.); 7.99 (d, 2H, J=8.1, arom.); 8.18 (s, 1H,H-8); 8.69 and 8.70 (2×s, 1H, H-2).

¹³C NMR (125.8 MHz, CDCl₃): 21.62 and 21.70 (2×CH₃); 34.21 and 34.34(CH₂ from alanyl); 37.66 and 37.75 (CH₂-2′); 51.12 (CH from alanyl);63.91 (CH₂-5′); 66.88 and 67.08 (2×CH₂Ph); 74.99° (CH-3′); 83.03 and83.06 (CH-4′); 84.76 and 84.79 (CH-17); 126.31 and 126.58 (2×C-p-arom.);128.03, 128.14, 128.30, 128.32, 128.42, 129.26, 129.59 and 129.78(8×CH-arom.); 133.38 and 133.43 (C-5); 135.27 and 136.28 (2×C-i-arom.);142.39 and 142.42 (CH-8); 144.16 and 144.53 (2×C-i-arom.); 150.18 and150.22 (C-4); 151.99 (CH-2); 156.07 and 156.09 (NCO); 157.75 (C-6);165.88 and 166.10 (CO from toluyl); 171.10 (COOBn).

IR (CDCl₃): 3429, 3032, 3013, 1721, 1612, 1599, 1500, 1456, 1408, 1387,1335, 1269, 1102, 1021, 938, 841, 646.

Anal. calculated for C₄₄H₄₁N₅O₉ (783.8): C, 67.42%; H, 5.27%; N, 8.93%;found: C, 67.07%; H, 5.46%; N, 8.71%.

Example 19 Production of(R,S)-3-(9-Benzylpurin-6-yl)-2-[(tert-butoxycarbonyl)amino]propanoicacid

Benzyl(R,S)-3-(9-benzylpurin-6-yl)-2-[(tert-butoxycarbonyl)amino]propanoate(1.9 g, 3.9 mmol) obtained in Example 1-2 in ethanol (140 ml) washydrogenated under slight overpressure in the presence of Pd/C catalyst(10 wt %, 180 mg) for 6 hr (the progress was monitored by TLC). Thecatalyst was filtered off through Celite pad and the filtrate wasevaporated in vacuo and crystallized from ethanol to give the titlecompound (1.38 g, yield 89%) as white crystals.

m.p. 172-175° C.

MS (FAB): 398 (16, M+1); 342 (19); 281 (7, M-NHBoc); 252 (19); 225 (23);135 (6); 91 (100, Bn).

HRMS (FAB): for C₂₀H₂₃N₅O₄ calculated 398.1828, found 398.1840.

¹H NMR (200 MHz, DMSO-d): 1.28 (s, 9H, 3×CH₃-Boc); 3.42 (dd, 1H, J=7.8and 14.9, CH _(A)H_(B)CH); 3.57 (dd, 1H, J=6.9 and 14.9, CH_(A) H_(B)CH); 4.75 (m, 1H, CHCH₂); 5.50 (s, 2H, CH ₂Ph); 7.20-7.33 (m, 5H,arom.); 8.73 (s, 1H, H-8); 8.86 (s, 1H, H-2).

¹³C NMR (50.3 MHz, DMSO-d₆): 28.29 (CH₃); 34.48 (CH ₂CH); 46.71 (CH₂Ph); 52.00 (CHCH₂); 78.32 (C(CH₃)); 127.89, 128.18 and 128.98(3×CH-arom.); 132.51 (C-5); 136.71 (C-arom.); 146.20 (CH-8); 150.72(C-4); 151.67 (CH-2); 155.40 (COO-tBu); 157.73° (C-6); 173.27 (COOH).

IR (KBr): 3210, 2980, 2932, 1726, 1701, 1653, 1599, 1532, 1504, 1455,1406, 1368, 1335, 1161, 1050.

Anal. calculated for C₂₀H₂₃N₅O₄ (397.4): C, 60.44%; H, 5.83%; N, 17.62%;found: C, 60.22%; H, 5.92%; N, 17.36%.

Example 20 Production of(R,S)-2-tert-butoxycarbonylamino-3-(9H-purin-6-yl)propionic acid

Benzyl(R,S)-3-[9-(tetrahydropyran-2-yl)purin-6-yl]-2-[(tert-butoxycarbonyl)amino]propanoate(867 mg, 1.8 mmol) obtained in Example 14 in ethanol (120 ml) washydrogenated under slight overpressure in the presence of Pd/C catalyst(10 wt %, 90 mg) for 6 hr. The catalyst was filtered off through Celitepad and the filtrate was evaporated in vacuo and crystallized frommethanol/ethyl acetate to give the title compound (465 mg, yield 84%) aswhite crystals.

m.p. 186-189° C. with decomposition.

MS (FAB) 308 (21, M+1); 252 (50); 208 (23, M-Boc+2H); 191 (35); 162(47); 135 (76)

HRMS (FAB): for C₁₃H₁₈N₅O₄ calculated 308.1359; found 308.1352.

¹H NMR (500 MHz, DMSO-d₆): 1.30 (s, 9H, 3×CH₃ from tBu); 3.40 (dd, 1H,J=8.1 and 14.5, CH _(A)H_(B)); 3.50 (dd, 1H, J=3.5 and 14.5, CH_(A) CH_(B)); 4.70 (br, 1H, CH from alanyl); 7.19 (d, 1H, J 8.3, NH); 8.55 (brs, 1H, H-8); 8.79 (s, 1H, H-2); 13.48 (v br, 1H, COOH).

¹³C NMR (125.8 MHz, DMSO-d₆): 28.07 (CH₃); 34.62 (CH₂ from alanyl);51.81 (CH from alanyl); 78.09 (C from tu); 151.29 (C-4, HMBCexperiment); 151.55 (CH-2); 155.17 (CO-tBu); 157.08 (C-6, HMBCexperiment); 173.13 (COOH).

IR (KBr): 3257, 3978, 2815, 2557, 1928, 1735, 1711, 1625, 1573, 1532,1447, 1383, 1328, 1298, 1250, 1164, 1045, 809, 640.

Anal. calculated for C₁₃H₁₇N₅O₄ (307.3): C, 50.81%; H, 5.58%; N, 22.79%;found: C, 50.77%; H, 6.05%; N, 22.35%;

Example 21 Production of (R,S)-2-amino-3-(9-benzylpurin-6-yl)propanoicacid trifluoracetate

TFA (0.8 ml) was added at 0° C. to(R,S)-3-(9-benzylpurin-6-yl)-2-[(tert-butoxycarbonyl)amino]propanoicacid (120 mg, 0.3 mmol) obtained in Example 19 in CH₂Cl₂ (8 ml). Thereaction mixture was stirred at ambient temperature for 1 hr. Then thesolvent was evaporated in vacuo and the residue was codestileted withCH₂Cl₂. The crude product was recrystallized from ethyl acetate/methanolto give the title compound (95 mg, yield 72%) as white crystals.

m.p. 243-244° C.

MS (FAB): 298-(100, M+1); 252 (17, M−COOH); 225 (33); 157 (12); 135(10); 91 (98, Bn).

HRMS (FAB): for C₁₅H₁₆N₅O₂ calculated 298.1304; found 298.1307.

¹H NMR (200 MHz, DMSO-d₆): 3.61 (dd, 1H, J=6.9 and 16.4, CH_(A)H_(B)CH); 3.75 (dd, 1H, J=5.5 and 16.4, CH_(A) H _(B)CH); 4.64 (t,1H, J=5.7, CHCH₂); 5.52 (s, 2H, CH₂Ph); 7.29-7.38 (m, 5H, arom.); 8.44(v br, NH₃ ⁺); 8.78 (s, 1H, H-8); 8.87 (s, 1H, H-2).

¹³C NMR (50.3 MHz, DMSO-d₆): 32.44 (CH ₂CH); 46.80 ( CH ₂Ph); 50.35(CHCH₂); 127.96, 128.24 and 129.02 (3×CH-arom.); 132.41 (C-5); 136.68(C-arom.); 146.50 (CH-8); 150.84 (C-4); 151.93 (CH-2); 155.49 (C-6);170.43 (CHCOO).

IR (KBr): 1732, 1692, 1603, 1530, 1506, 1406, 1335, 1264, 1197, 1183,1131.

Anal. calculated for C₁₇H₁₆F₃Nr₅O₄ (411.3): C, 49.64%; H, 3.92%; N,17.03%; found C, 49.38%; H, 3.97%; N, 16.77%.

Example 22 Production of (R,S)-2-amino-3-(9-benzylpurin-6-yl)propanoicacid hydrochloride

(R,S)-3-(9-Benzylpurin-6-yl)-2-[(tert-butoxycarbonyl)amino]propanoicacid (398 mg, 1 mmol) obtained in Example 19 in ethyl acetate saturatedwith hydrochloric acid (aprox. 1.7 M) was stirred at ambient temperaturefor 8 hr, then the precipitate was filtered and recrystallized fromethanol to give the title compound (280 mg, yield 84%) as whitecrystals.

m.p. 231-235° C.

¹H NMR (200 MHz, DMSO-d₆): 3.68 (dd, 1H, J=6.4 and 16.4, CH_(A)H_(B)CH); 3.80 (dd, 1H, J=6.2, and 16.4, CH_(A) H _(B)CH); 4.64 (brs, 1H, CHCH₂); 5.53 (s, 2H, CH ₂Ph); 7.27-7.39 (m, 5H, arom.); 8.68 (brs, 3H, NH₃ ⁺); 8.81 (s, 1H, H-8); 8.86 (s, 1H, H-2). ¹³C NMR (50.3 MHz,DMSO-d₆): 32.40 (CH ₂CH); 46.79 (CH ₂Ph); 50.18 (CHCH₂); 127.96, 128.23and 129.02 (3×CH arom.); 132.36 (C-5); 136.71 (C arom.); 146.51 (CH-8);150.82 (C-4); 151.90 (CH-2); 155.60 (C-6); 170.31 (COO).

Anal. calculated for C₁₅H₁₆ClN₅O₂ (333.8): C, 53.98%; H, 4.83%; N,20.98%; Cl, 10.62%; found: C, 53.79%; H, 4.91%; N, 20.22%; Cl, 10.85%.

Example 23 Production of (R,S)-2-amino-3-(9H-purin-6-yl)propanoic acidtrifluoracetate

The reaction in the same manner as in Example 21 gave the title compound(90 mg, yield 86%) as white crystals.

m.p. 163-166° C.

MS (FAB): 208 (100, M+1); 181 (36); 162 (33); 149 (18); 135 (65); 133(45); 36 (110).

MS (FAB): for C₈H₁₀N₅O₂ calculated 208.0835; found 208.0848.

¹H NMR (500 MHz, DMSO-d₆): 3.62. (dd, 1H, J=6.9 and 16.5, CH _(A)H_(B));3.73 (dd, 1H, J=5.3 and 16.5, CH_(A) H _(B)); 4.64 (dd, 1H, J. 5.3 and6.4, HCH₂); 8.46 (v br, NH₃ ⁺); 8.60 (s, 1H, H-8) 8.83 (s, 1H, H-2).

¹³C NMR (125.7 MHz, DMSO-d₆): 32.35 (CH₂); 50.09 (CH from alanyl);145.20 (CH-8); 151.51 (CH-2); 153.33 (C-6, HMBC experiment); 170.22(CO).

IR (KBr): 3424, 3183, 3159, 2853, 2698, 2632, 1698, 1685, 1608, 1517,1491, 1425, 1399, 1338, 1264, 1224, 1196, 1133, 836, 796, 723, 637.

Anal. calculated for C₁₀H₁₀F₃N₅O₄ (321.2): C, 37.39%; H, 3.14%; N,21.80%; found C, 37.44%; H, 3.22%; N, 21.41%.

Example 24 Production of (R,S)-2-amino-3-(9H-purin-6-yl)propanoic aciddihydrochloride

The reaction in the same manner as in Example 22 gave the title compound(yield 99%) as white crystals.

m.p. more than 280° C.

¹H NMR (200 MHz, DMSO-d₆): 3.74 (dd, 1H, J=6.4 and 16.4, CH _(A)H_(B));3.85 (dd, 1H, J=5.9 and 16.4, CH_(A) H _(B)); 4.69 (br s, 1H, CHCH₂);5.90 (v br, NH₂ ⁺); 8.71 (br s; NH₃ ⁺); 8.88 (s, 1H, H-8) 8.94 (s, 1H,H-2).

¹³C NMR (50.3 MHz, DMSO-d₆): 32.40 (CH₂); 50.12 (CH from alanyl); 128.79(C-5); 146.11 (CH-8); 151.29 (CH-2); 153.01 and 153.67 (C-6 and C-4);170.14 (CO).

Example 25 Production of(R,S)-2-amino-3-[9-(2,3,5-tri-O-acetyl-A-D-ribofuranosyl)purin-6-yl]propionicacid benzyl ester trifluoracetate

TFA (1.8 ml, 2.3 mmol) was slowly added at 0° C. to benzyl(R,S)-3-[9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purin-6-yl]-2-[(tert-butoxycarbonyl)amino]propanoate(1.4 g, 2.1 mmol) obtained in Example 15 in CH₂Cl₂ (30 ml). The reactionmixture was stirred at room temperature overnight. Then the solvent wasevaporated in vacuo and the residue was codestileted with CH₂Cl₂. Thecrude product was chromatographed on a silica gel column(methanol/chloroform, 1:9) to give the title compound (1.4 g, yield 97%)as a yellowish amorphous solid.

MS (FAB): 556 (14, M+1); 298 (26); 259 (25); 162 (33); 139 (100); 135(57); 97 (74); 91 (98, Bn).

HRMS (FAB): for C₂₆H₃₀N₅O₉ calculated 556.2044, found 556.2057.

¹H NMR (500 MHz, CDCl₃): 2.06 (d, 3H, J=2.08, CH₃CO); 2.10 (s, 3H,CH₃CO); 2.15 (d, 3H, J=2.23, CH₃CO); 3.88-4.04 (m, 2H, CH₂ from alanyl);4.39-4.49 (m, 3H, H-4′+H-5′); 4.70 (br s, 1H, CH form alanyl); 5.04 (dd,1H, J=12.3 and 15.1, CH _(A)H_(B)Ph); 5.16 (dd, 1H, J=9.0 and 11.6,CH_(A) H _(B)Ph); 5.64. (dd, 1H, J=4.5 and 9.5, H-3′); 5.91 (2×t, 1H,J=5.5, H-2′); 6.21 (2×d, 1H, J=5.2, H-1′); 7.09-7.25 (m, 5H, arom.);8.25 (s, 1H, H-8); 8.67 and 8.69 (2×s, 1H, H-2).

¹³C NMR (125.8 MHz, CDCl₃): 20.22, 20.45 and 20.65 (3×CH₃) 30.91 (CH₂from alanyl); 51.13 and 51.17 (CH from alanyl); 63.03 and 63.07(CH₂-5′); 68.42 and 68.46 (H ₂Ph); 70.57 and 70.63 (CH-3′); 72.90 and73.15 (CH-2′); 80.51 and 80.57 (CH-4′); 86.30 and 86.58 (CH-1′); 128.37,128.41, 128.52, 128.55 and 128.65 (5×CH-arom.); 132.32 and 132.40 (C-5);134.08 and 134.11 (C-arom.); 143.32 (CH-8); 150.43 (C-4); 151.98 (CH-2);156.15 (C-6); 168.19 (COOBn); 169.53, 169.66 and 170.51 (3×COCH₃).

IR (CHCl₃): 3031, 3009, 1751, 1680, 1603, 1499, 1457, 1374, 1338, 1226,1206, 1143, 801, 644.

Example 26 Production of methyl(R,S)-3-{4-[9-(tetrahydropyran-2-yl)purin-6-yl]phenyl}-2-[(tert-butoxycarbonyl)amino]propanoate

The reaction under the same conditions as in Example 2-2 except that6-iodo-9-(tetrahydropyran-2-yl)purine (1.33 g, 3 mmol) and methyl(R,S)-2-[(tert-butoxycarbonyl)amino]-3-[4-(trimethylstannanyl)phenyl]propionate (878 mg, 2.66 mmol)were used instead of 9-benzyl-6-iodopurine (547 mg, 1.65 mmol) andmethyl(R,S)-2-[(tert-butoxycarbonyl)amino]-3-[4-(trimethylstannanyl)phenyl]propionate(827 mg, 1.87 mmol) of Example 2-2, followed by working up gave thetitle compound (687 mg, yield 53%) as white crystals.

m.p. 144-147° C.

MS (EI): 481 (0.5, M); 364 (4); 341 (6); 324 (7); 294 (15); 280 (13);238 (11); 210 (100).

HRMS (EI): for C₂₅H₃₁N₅O₃ calculated 481.2325, found 481.2302.

¹H NMR (200 MHz, CDCl₃): 1.43 (s, 9H, (CH₃)₃); 1.65-1.87 (m, 3 Hi CH₂from THP); 2.02-2.22° (m, 3H, CH₂ from THP); 3.20 (br d, 2H, J=4.8, CH₂from alanyl); 3.73 (s, 3H, OCH₃); 3.85 (dd, 1H, J=3.0 and 11.4, H-5′a),4.21 (dt, 1H, J=2.0 and 11.4, H-5′b); 4.66 (dd, 1H, J=5.9 and 13.8,CHNH); 5.05 (d, 1H, J=7.9, NH); 5.86 (dd, 1H, J=3.4 and 9.5, H-1′); 7.33(d, 2H, J=8.3, arom.); 8.34 (s, 1H, H-8); 8.73 (d, 2H, J=8.3, arom.);9.01 (s, 1H, H-2).

¹³C NMR (50.3 MHz, CDCl₃): *22.77 and 24.83 (2×CH₂ THP); 28.26 ((CH₃)₃);31.81 (CH₂ THP); 38.12 (CH₂ from alanyl); 52.27 (OCH₃); 54.28 (CHNH);68.87 (CH₂-5′); 79.98 (C(CH₃)₃); 81.92 (CH-1′); 129.65 and 129.93(2×CH-arom.); 130.97 (C-5); 134.46 (C-1-arom.); 139.19 (C-p-arom.);141.98 (CH-8); 151.64 (C-4); 152.37 (CH-2); 154.52 (C-6); 155.04 (COOfrom Boc); 172.09 (COOMe).

IR (CHCl₃): 3436, 2983, 1743, 1710, 1584, 1560, 1499, 1449, 1166.

Anal. calculated for C₂₅H₃₁N₅O₅ (481.5): C, 62.36%; H, 6.49%; N, 14.54%;found: C, 62.37%; H, 6.72%; N, 14.14%.

Example 27 Production of methyl(R,S)-3-{4-[9-(2,3,5-tri-O-acetyl-p-D-ribofuranosyl)purin-6-yl]phenyl}-2-[(tert-butoxycarbonyl)amino]propanoate

The reaction under the same conditions as in Example 2-2 except that6-iodo-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purine (1.33 g, 3 mmol)and methyl(R,S)-2-[(tert-butoxycarbonyl)amino]-3-[4-(trimethylstannanyl)phenyl]propionate.(1.34 g, 2.66 mmol) were used instead of 9-benzyl-6-iodopurine (547 mg,1.65 mmol) and methyl(R,S)-2-[(tert-butoxycarbonyl)amino]-3-[4-(trimethylstannanyl)phenyl]propionate(827 mg, 1.87 mmol) of Example 2-2, followed by working up gave thetitle compound (961 mg, yield 55%) as a colorless amorphous solid.

MS (FAB): 656 (3, M+H); 600 (3); 342 (34); 259 (19); 238 (22); 210 (38);139 (92); 97 (79).

HRMS (FAB): for C₃₁H₃₇N₅O₁₁ calculated 656.2568, found 656.2525.

¹H NMR (200 MHz, CDCl₃): 1.43 (s, 9H, (CH₃)₃); 2.10, 2.15 and 2.17 (3×s,3×3H, 3×CH₃ from Ac); 3.19 (m, 2H, CH₂); 3.73 (s, 3H, OCH₃); 4.35-4.53(m, 2H, H-5′ and H-4′); 4.66 (dd, 1H, J=5.4 and 13.7, CHCH₂); 5.03 (d,1H, J=8.1, NH); 5.72 (dd, 1H, J=4.4 and 5.4, H-3′); 6.02 (t, 1H, J=5.4,H-2′); 6.30 (d, 1H, J=5.4, H-1′); 7.33 (d, 2H, J=8.3, arom.); 8.28 (s,1H, H-8); 8.71 (d, 2H, J=8.3, arom.); 9.02 (s, 1H′, H-2).

¹³C NMR (125.8 MHz, CDCl₃): 20.34, 20.49 and 20.71 (3×H ₃CO); 28.27 (CH₃from tBu); 38.15 (CH ₂CHNH); 52.24 (OCH₃); 54.25 (CHNH); 63.01 (CH2-5′);70.58 (CH-3′); 73.03 (CH-2′); 79.97 (C(CH₃)₃); 80.33 (CH-4′); 86.36(CH-1′); 129.67 and 129.94 (CH-arom.); 131.48 (C-arom.); 134.15 (C-5);139.47 (C-arom.); 142.48 (CH-8); 151.95 (C-4); 152.61 (CH-2); 155.00(C-6); 169.33, 169.54 and 170.27 (3×CO from Ac); 172.06 (COOMe).

IR (CHCl₃): 3438, 3010, 2984, 1749, 1711, 1673, 1584, 1498, 1369, 1234,1167, 1062, 925, 866, 804, 667, 603.

Example 28 Production of(R,S)-3-[4-(9-benzylpurin-6-yl)phenyl]-2-[(tert-butoxycarbonyl)amino]propanoic acid

Methyl(R,S)-3-[4-(9-benzylpurin-6-yl)phenyl]-2-[(tert-butoxycarbonyl)amino]propanoate(245 mg, 0.5 mmol) obtained in Example 2-2 was dissolved in THF (17 ml)and 0.2 M aqueous solution of NaOH (4.5 ml) was added. The reactionmixture was stirred at room temperature for 1.5 hr. Then 1% aqueous HClwas added to adjust to pH 4, and the mixture was diluted with water (50ml) and washed with ethyl acetate (80 ml). The organic extract wasevaporated and recrystallized from ethyl acetate to give the titlecompound (220 mg, yield 93%) as white crystals.

m.p. 214-216° C.

MS (FAB): 474 (14, M+1); 418 (30); 328 (8), 300 (11, M-CHCOOH(NHBoc)+1);91 (100, Bn).

HRMS (FAB): for C₂₆H₂₈N₅O₄ calculated 474.2141; found 474.2139.

¹ NMR (200 MHz, DMSO-d₆): 1.31 (s, 9H, 3×CH₃-Boc); 2.93 (dd, 1H, J=10.4and 13.8, CH _(A)H_(B)CH); 3.13 (dd, 1H, J=4.5 and 13.8, CH_(A) H_(B)CH); 4.18 (m, 1H, CHNH); 5.55 (s, 2H, CH ₂Ph); 7.22 (d, 1H, J=8.3,arom.); 7.28-7.40 (m, 4H, arom.); 7.47 (d, 2H, J=8.2, arom.); 8.75 (d,2H, J=8.2, arom.); 8.82 (s, 1H, H-8); 8.97 (s, 1H, H-2); 12.70 (very br,1H, COOH).

¹³C NMR (50.3 MHz, DMSO-d₆): 28.34 (CH₃); 36.63 (CH ₂CH); 46.71 (CH₂Ph); 55.14 (CH₂ CH); 78.31 (C(CH₃)₃); 127.88, 128.16, 128.99, 129.42and 129.68 (5×CH-arom.); 130.38 (C-5); 133.76, 136.74 and 141.70(3×C-arom.); 146.61 (CH-8); 152.20 (CH-2); 152.46, 152.88 and 155.69(C-4, C-6 and COOtBu); 173.71 (COOH).

IR (KBr): 3393, 2979, 2932, 1707, 1585, 1560, 1509, 1457, 1367, 1328,1243, 1187, 1165, 1055, 727.

Anal. calculated for C₂₆H₂₇N₅O₄ (473.5): C, 65.95%; H, 5.75%; N, 14.79%;found: C, 65.72%; 5.83%; 14.65%.

Example 29 Production of(R,S)-2-amino-3-[4-(9-benzylpurin-6-yl)phenyl]propionic acidtrifluoracetate

(R,S)-3-[4-(9-Benzylpurin-6-yl)phenyl]-2-[(tert-butoxycarbonyl)amino]propanoic acid (115 mg, 0.24 mmol)obtained in Example 28 was dissolved in CH₂Cl₂ (9 ml) and TFA (1 ml) wasadded at 0° C. The reaction mixture was stirred at room temperature for5 hr. Then the solvent was evaporated in vacuo and the residue wascodestileted with CH₂Cl₂. The crude product was recrystallized fromethyl acetate/methanol to give the title compound (89 mg, yield 77%) aswhite crystals.

m.p. 194-197° C.

MS (FAB): 374 (39, M+1); 300 (10, M-CHCOOH(NHBoc)+1); 91 (100, Bn)

HRMS (FAB): for C₂₁H₂₀N₅O₂ calculated 374.1617; found 374.1660.

¹H NMR (200 MHz, DMSO-d₆): 3.21 (m, 2H, CH₂); 4.28 (t, 1H, J=(CHCO,CH₂)=6.9, CHCO); 5.55 (s, 2H, CH ₂Ph); 7.29-7.41 (m, 5H, arom.); 7.50(d, 2H, J=8.3, arom.); 8.41 (v br, NH₃ ⁺); 8.79 (d, 2H, J=8.3, arom.);8.85 (s, 1H, H-8); 9.01 (s, 1H, H-2).

¹³C NMR (125.8 MHz, DMSO-d₆): 36.06 (CH ₂CH); 46.76 (CH₂Ph); 53.29(CHCH₂); 117.44 (q, J=298.8, CF ₃COOH); 127.97, 128.20, 129.01, 129.79and 130.10 (CH-arom.); 130.47 (C-5); 134.59 (C-arom.); 136.72 (C-arom.);138.45 (C-arom.); 146.78 (CH-8); 152.24 (CH-2); 152.54 and 152.68 (C-4and C-6); 158.41 (q, J=31.5, CF₃ COOH); 170.62 (CHCOOH).

IR (KBr): 3434, 3035, 2938, 1679, 1583, 1515, 1498, 1454, 1401, 1326,1204, 1138, 836, 800, 722, 699.

Anal. calculated for C₂₃H₂₀F₃N₅O₄ (487.4): C, 56.67%; H, 4.14%; N,14.37%; found: C, 56.42%; H, 4.14%; N, 14.14%.

Example 30 Production of(R,S)-2-amino-3-[4-(9-benzylpurin-6-yl)phenyl]propionic acidhydrochloride

(R,S)-3-[4-(9-Benzylpurin-6-yl)phenyl]-2-[(tert-butoxycarbonyl)amino]propanoicacid (75 mg, 0.16 mmol) obtained in Example 28 was dissolved in ethylacetate saturated with hydrochloric acid (aprox. 1.7 M). The reactionmixture was stirred at room temperature for 3 hr, then the formedprecipitate was filtered and recrystallized from methanol/ethyl acetateto give the title compound (65 mg, yield 100%) as white crystals.

¹H NMR (200 MHz, DMSO-d₆): 3.26 (d, 2H, J=6.1, CH ₂CH); 4.25 (m, 1H,CHCH₂); 5.57° (s, 2H, CH ₂Ph); 7.30-7.39 (m, 5H, arom.); 7.53 (d, 2H,J=8.3, arom.); 8.59 (br, NH₃ ⁺); 8.77 (d, 2H, J=8.3, arom.); 8.90 (s,1H, H-8); 9.02 (s, 1H, H-2).

¹³C NMR (50.3 MHz, DMSO-d₆): 35.86 (CH ₂CH); 46.83 (CH₂Ph); 53.20(CHCH₂); 128.00, 128.24, 129.04, 129.85 and 130.20 (5×CH-arom.); 130.42(C-5); 134.07 (C-arom.); 136.67 (C-arom.); 138.75 (C-arom.); 147.11(CH-8); 151.97 (CH-2); 152.42 and 152.66 (C-4 and C-6); 170.51 (COO).

Example 31 Production of(S)-2-amino-3-[4-(9-benzylpurin-6-yl)phenyl]propionic acid hydrochloride

Dioxane/water (2:1, 5 ml) was added through septum to an argon purgedflask containing 9-benzyl-6-chloropurine (59 mg, 0.24 mmol),(S)-4-boronophenylalanine (63 mg, 0.3 mmol), K₂CO₃ (88 mg, 0.64 mmol)and Pd(PPh₃)₄ (23 mg, 0.02 mmol). The mixture was stirred at 90° C. for4 hr, diluted with water (40 ml) and pH of the solution was adjustedwith aqueous HCl (2%) to 4. The mixture was washed with ethyl acetateand the solvent was evaporated in vacuo from the water part. The solid15, residue was dissolved in water (1.5 ml) and crystallized from thesolution at room temperature during 48 hr to give the title compound (50mg, yield 61%) as white crystals.

¹H NMR (400 MHz, DMSO-d₆): 3.15 (dd, 1H, J=7.0 and 14.1, CH_(A)H_(B)CH); 3.26 (dd, 1H, J=5.4 and 14.1, CHAH_(B)CH); 3.95 (t, 1H,J=6.1; CHCH₂); 5.54 (s, 2H, CH ₂Ph); 7.30-7.40 (m, 5H, arom.); 7.50 (d,2H, J=8.2, arom.); 8.75 (d, 2H, J=8.2, arom.); 8.82 (s, 1H, H-8); 8.96(s, 1H, H-2).

¹³C NMR (100.6 MHz, DMSO-d₆): 35.75 (CH ₂CH); 46.48 (CH₂Ph); 53.18(CHCH₂); 127.67, 127.90, 128.71, 129.46 and 139.80 (5×CH-arom.); 130.19(C-5); 134.23 (C-arom.); 136.42 (C-arom.); 138.45 (C-arom.); 146.44(CH-8); 151.94 (CH-2); 152.26 and 152.46 (C-4 and C-6); 170.16 (CO).

INDUSTRIAL APPLICABILITY

The (purin-6-yl)amino acid of the present invention per se is useful asa pharmaceutical product such as an anti-cancer agent, antiviral agentand the like, or a production intermediate therefor, and the(purin-6-yl)amino acid can be produced easily according to the method ofthe present invention.

This application is based on patent application No. 2003-115403 filed inJapan, the contents of which are hereby incorporated by reference.

1. A (purin-6-yl)amino acid represented by formula (1)

wherein R¹ is hydrogen, alkyl, optionally substituted aryl, optionallysubstituted heteroaryl or aralkyl; R² and R³ are hydrogen, halogen,optionally substituted alkyl, optionally substituted aryl, optionallysubstituted heteroaryl, optionally substituted amino or optionallysubstituted hydroxy; and R is —NH₂, —NHR′ or —NR′R″, said R′ and R″ areprotecting group for amino group. Y is alkylene, alkenylene oralkynylene; A is optionally substituted phenylene; m and n are 0 or 1;and R⁴ is hydrogen or organic group, or its salt.
 2. The(purin-6-yl)amino acid according to claim 1, which is represented byformula (2):

wherein R¹, R², R³ and R⁴ are as defined above; and R⁶ and R⁷ areoptionally substituted aryl, or its salt.
 3. The (purin-6-yl)amino acidaccording to claim 1, which is represented by formula (3):

wherein R¹, R², R³, R⁴, Y and m are as defined above; and R⁸ and R⁹ arehydrogen or protecting group for amino group, or its salt.
 4. The(purin-6-yl)amino acid according to claim 3, wherein m is 1 and Y ismethylene, or its salt.
 5. The (purin-6-yl)amino acid according to claim3, wherein m is 1 and Y is trimethylene, or its salt.
 6. The(purin-6-yl)amino acid according to claim 3, wherein m is 1 and Y ispropynylene, which is represented by formula (4):

wherein R¹, R², R³, R⁴, R⁸ and R⁹ are as defined above, or its salt. 7.The (purin-6-yl)amino acid according to claim 1, which is represented byformula (5):

wherein R¹, R², R³, R⁴, R⁸, R⁹, Y and m are as defined above, or itssalt.
 8. The (purin-6-yl)amino acid according to claim 7, wherein m is 1and Y is methylene, or its salt.
 9. A synthetic method of the(purin-6-yl)amino acid described in claim 2, which is made a halogenatedpurine compound represented by formula (6):

wherein X is halogen atom; and R², R³ and R⁴ are as defined above; toreact with an amino acid derivative represented by formula (7):

wherein R¹, R⁶ and R⁷ are as defined above.
 10. A synthetic method ofthe (purin-6-yl)amino acid described in claim 3, which is made thehalogenated purine compound represented by formula (6) to react with ahalogenated amino acid derivative represented by formula (8):

wherein R¹, R⁸, R⁹, X, Y and m are as defined above.
 11. A syntheticmethod of the (purin-6-yl)amino acid described in claim 5, which is madethe halogenated purine compound represented by formula (6) to react withan amino acid represented by formula (9):

wherein R¹, R⁶ and R⁷ are as defined above.
 12. A synthetic method ofthe (purin-6-yl)amino acid described in claim 7, which is made thehalogenated purine-compound represented by formula (6) to react with anamino acid compound represented by formula (10):

wherein R¹, R⁸, R⁹, Y and m are as defined above; W is —Sn(R⁵)₃,—B(OH)₂, —B(OR⁵)₂ or —MgX; R⁵ is lower alkyl; and X is as defined above.